JUPITER'S MOONS
IO, Jupiter's closest moon, is the most geologically active bodies in the Solar System. It has massive volcanic plumes and undergoes frequent global resurfacing. The heat in Io is about 200 times what would be expected from heat due to radioactive decay[4]. This heat is generated from the flexing of interior due to its gravitational interaction with Jupiter, Tidal Heating.
Io represents the best example of tidal heating. Io orbits around Jupiter which is a very large body with a mass that is equivalent to about 320 earths[5]. From Newton's Law of Universal Gravitation, gravitational force is directly proportional to mass and inversely proportional to distance between the two bodies. Considering the huge difference in size as well as their proximity, it can be deduced that the Jupiter's pull on Io will be tremendous.
Io represents the best example of tidal heating. Io orbits around Jupiter which is a very large body with a mass that is equivalent to about 320 earths[5]. From Newton's Law of Universal Gravitation, gravitational force is directly proportional to mass and inversely proportional to distance between the two bodies. Considering the huge difference in size as well as their proximity, it can be deduced that the Jupiter's pull on Io will be tremendous.
Io is in an orbital resonance of 1:2:4 with Europa and Ganymede and this continues to pump its eccentricity giving rise to widely varying distances between itself and Jupitar. This in turn leads to huge tidal forces that cause bulges on the surface of Io up to 100m high. Compare this with the highest tidal bulge experienced on Earth's oceans, which is more deformable that Io's solid mass, is about 18m high[6].
Io has an orbital period of 1.8 days (compare with Earth’s moon of 27 days), therefore, it goes through this cycle of distortion in that amount of time. This distortion causes a great amount of internal heat in Io as the layers of rock move. This tremendous amount of tidal heat is responsible for the rugged terrain of Io which is covered with lava flows and lakes, calderas and mountains.
It is noteworthy that, when tidal heat is produced inside the satellite, Io loses orbital energy and moves deeper into Jupiter’s gravitational well (tidal heat poses friction to rotation). In addition, tidal dissipation in Jupiter tends to move Io outward and to decelerate the orbital motion while the spin of Jupiter decreases, similar to the Earth-Moon system.
EUROPA, another moon of Jupitar, is smooth, highly reflective and slightly smaller than our moon. It also boasts of a young surface. Being far from the sun, it was assumed to be globally frozen. However, it has been found that beneath the moon's frozen shell, there is an ocean with more liquid water than is contained in the whole of Earth. The Galileo mission
discovered evidence of geological activities on the surface such as great ridges and cracks due to tectonic stretching and the chaos terrain which could be as a result of some sort of convection. Galileo also uncovered areas where liquid water from the subsurface ocean had risen to the surface.
Tidal heating is the most important heat source on Europa. Tidal flexing due to Jupiter's differential gravitational pull on Europa caused by its elliptical orbit which was generated by its orbital resonance with Ganymede and Io.
Europa gives an insight as to one of the ways by which orbital energy gives rise to heat. The study the double ridges of Europa shows that shear heating along faults between the ridges dissipates the orbital energy[7]. Therefore, these features represent some of the hottest parts of the moon. These Europan double ridges can be likened to the Tiger Stripes of Enceladus.
The tidal forces on Europa due to it's relationship with Jupiter is 1000 times stronger than that felt on our moon due to Earth[8].
Tidal heating is the most important heat source on Europa. Tidal flexing due to Jupiter's differential gravitational pull on Europa caused by its elliptical orbit which was generated by its orbital resonance with Ganymede and Io.
Europa gives an insight as to one of the ways by which orbital energy gives rise to heat. The study the double ridges of Europa shows that shear heating along faults between the ridges dissipates the orbital energy[7]. Therefore, these features represent some of the hottest parts of the moon. These Europan double ridges can be likened to the Tiger Stripes of Enceladus.
The tidal forces on Europa due to it's relationship with Jupiter is 1000 times stronger than that felt on our moon due to Earth[8].